1. Field of the Invention
The invention relates to photoreactive devices, translucent members, ornaments, anticorrosive devices, devices for reducing oxygen and devices for controlling the growth of microorganisms.
2. Related Art Statement
Recently, it has been proposed a photo cathode anticorrosion process using a membrane of titanium dioxide. In Japanese patent application publication “Kokai” A 10153/1994, a film containing titanium dioxide in an equivalent amount of 1 mg/m2 calculated as metal titanium is formed on the surface of a material of stainless steel. When irradiating light onto the surface of the stainless steel (that is, the surface of the film), the stainless steel acts as a cathode and the film acts as an anode, so that the immersion potential of the stainless steel shifts as large as −300 mV. The corrosion of the stainless steel may be prevented by the photo cathode process, according to the publication.
According to Japanese patent application “Kokai” A 71684/1999, the above membrane of titanium dioxide does not prevent the corrosion of the underlying stainless steel material when sufficient light intensity is not available. For overcoming this problem, an intermediate layer is formed between the stainless steel material and the surface film containing titanium dioxide. The intermediate layer contains a metal of iron, vanadium or copper. In such device, the metal contained in the intermediate layer may have a relatively lower valence under illumination (reduced) and a higher valence without illumination (oxidized), according to the publication. Therefore, it is stated that iron, copper or vanadium discharges electrons when the illumination is shut off and the discharged electrons are introduced into the underlying stainless steel material so as to maintain the anticorrosion effect without light.
On the other hand, tungsten oxide is reduced electrochemically and reacts with electrons and protons so that it is converted to its tungsten bronze structure and colored.